1. Field of the Invention
This invention relates generally to drive mechanisms for cryogenic refrigerators, and more particularly to drive mechanisms for driving the compressor and expander pistons of cryogenic refrigerators.
2. Description of the Related Art
Modified Stirling cycle cryogenic cooling systems of the type described in U.S. Pat. No. 3,074,244 have proven to have substantial advantages over other types of refrigeration systems. Such cryogenic cooling systems are inherently lighter, less expensive, more reliable and more efficient than other available types. They also have the additional important advantages that they operate using non-hazardous working gases, such as helium or nitrogen, and require no condenser or evaporator coils.
Such modified Stirling cycle cooling systems are generally driven by electric motors through some form of gear drive and crankshaft arrangement. While this arrangement provides good performance for most applications, it results in design difficulties in certain applications in which the refrigerator incorporates a plurality of compressor expander piston pairs and in which compactness is of critical importance.